Process for treating polyamide fibers



PROCESS FOR TREATING POLYAMIDE FIBERS Georg Hennemann, Yelp, Netherlands, .assignor, by m'esne assignments, to American Enka Corporation, Enka, N13,, a corporation of Delaware No Drawing. Application January 17, 1955 Serial No. 482,393

Claims priority, application Netherlands January 25, 1954 2 Claims. (Cl. 117--76) This invention relates broadly to the treatment of synthetic fibers to improve their ability to be carded and more particularly, to the treatment of synthetic fibers, e.g., polyamides.

Fibershereinafter referred .to are meant to apply to any sort of fiber-of arbitrary length, including endless threads.

In the past it has been very difficult to card synthetic fibers such as the polyamide fibers due to their tendency to adhere to each other or to'stick to parts of the apparatus. This tendency to stick, it has been found, increases with the fineness and the length of the fibers. The reason for these fibers having a tendency to adhere to each other or to stick to parts of the apparatus is not actually known. However, it is believed that these carding dilficulties are caused by the presence of active groups on the'fiber surface. These difficulties it has now been found can be eliminated by blocking these active groups, i.e., anion active or cation, present on the fiber surface.

Until now certain aftertreatments have been used for the purpose of improving the poor cardability, e.g., treatment with a polyphenyl sulfonic compound, .a kind of tanning material (Basyn treatment). However, the results of such treatments have been found to be very, un-

satisfactory. The fibers treated in this manner still have .the tendency to adhere to each other or to stick to parts of the apparatus. Morever, this treatment causes a dis coloration of the fibers. I r

It is, therefore, an object of this invention to improve the cardability of fibers.

Another object of this invention is to block the anion active or cation active groups present on a fiber surface.

A further object is to improve in particular, the cardability of polyamide fibers.

Other objects of the present invention will become apparent upon consideration of the following detailed description thereof.

' According to the process of the present invention the fibers are treated first with a polymeric polyactive substance, the active groups of which are opposite those of the fibers and, secondly, with a monomeric monoactive substance which has but one active group. The activity of this group is, of course, opposite that of the polymeric polyactive substance. As a result of this double treatment, it is not only possible to card the fibers better but also to avoid certain secondary actions of the polyactive substances. This preparation of the fiber surface also better adapts the fiber for subsequent treatment.

Due to the blocking by means of the polymeric polyactive substance of the opposite active groups of the fiber material, a tensioning of the surface of the fiber bodies is affected and consequently a stiffening of the fiber material. To overcome the stiffening of the fiber material the monomeric monoactive substance is applied to the fiber' material, thus blocking any remaining detrimental active groups and, depending upon the monomeric monoactive substance applied, simultaneously creates a less stiffened fiber with a smooth surface.

"In order to render the active groups on the fiber sur- United States Patent suitable for the aforementioned purpose.

Patented Oct. 20, 19,59

face more suitable for being blocked 'by the treating agents the fibers are first moistened with water,-subsequently dried and finally further heated in a dried condition. In drying andheating the fibers it is preferred to start the drying at a temperature of about 60 .C., which is subsequently raised to 105 C., and maintained there for a certain period, e.g., 30.minutes or more.

When dealing with the problem of thecardability of polyamide and like fibers which are generally known to have cation active groups on their surfaces the fibers are first treated in an acid medium with ,a polymeric polyanion active substance and thereafter with a monomeric monocation active substance.

Upon treating polyamide fibers in acid medium the fibers act as a polyvalent cation active body having a considerable density of cation active groups. Thus, the

treatment of the polyamide fibers with a polymeric polyanion active treating agent blocks the cation active groups of the fibers.

However, in each case the number of cation active groups of the textile fiber is small in comparison to the number of the anion active groups of the applied polymeric, polyanion active treating agent, so that a large number of anion active groups are themselves left unblocked. These anion active groups produce a fiber surface which is unfavorable for further textile treatment. Thus, to overcome thisunfavorable fiber surface the second treatment is made with a monomeric monocation active substance. The remaining anion active groups 'ofthepre-treated textile fibers are thereby blocked so that jactive substances polyvinyl compounds which may be produced from monomers of the general formula By the substitution of R R R and R it is possible to produce a great many variants many of which are Polymethylacrylic acid, polystyrene sulfona-te, copolymers from styrene and maleic acid and the like may be cited for example. When practicing the process according to the present invention it has been found that the best results are obtained when the compounds used are within certain quantitative limits. The pH of the first treating bath of the polymeric polyanion active substances should be maintained between 1 and 4 and preferably between 3 and'4. The concentration of the first bathis preferably from 0:5 to 2% by weight, calculated as dry matter. The treating temperature may be maintained between to 95 C., although preferably between and C. It also should be kept in mind that the fibers should not be dried after the first treatment but centrifuged whereupon the fibers which are still wet are treated with the second bath containing the monomeric monocation active substance.

For the blocking of the polymeric anionic active substance, it has been found that an inorganic and/or an organic monomeric monocation active substance may be used. inorganic monomeric monocation active substances are employed, e.g., aluminum sulfate, magnesium sulfate, and the like if the fiber is smooth and not curled or slightly curled, i.e., has the necessary smoothbecomes too high.

'proved quite successful.

also possible to obtain an length is of at least twelve carbon atoms. Beyond twenty carbon atoms in the chain length the fiber smoothness Organic monomeric monocation active substances containing a long chain radical having preferably from twelve to eighteen carbon atoms may be employed with advantage in the second treatment step. stances belong chiefly to the class known as cation active synthetic soaps. Among the organic monomeric monocation active substances which may be employed are the alkyl ammonium compounds, such as alkyl trimethyl ammonium compounds or salts thereof and alkyl pyridinium salts, e.g., dodecyl, tetradecyl, hexadecyl and octadecyl trimethyl ammonium chloride and dodecyl, tetradecyl, hexadecyl and octadecyl pyridinium chloride. Other quaternary ammonium compounds, such as triethyl octadecyloxymethyl ammonium chloride, phenyl benzyl dimethyl ammonium chloride, octadecyloxymethyl pyridinium chlo ride and stearoxy methyl pyridinium chloride have also The corresponding phosphonium, sulphonium and oxonium salts as long as they do not discolor the fibers to an undesirable degree may also be employed. Instead of chlorides one may also use other halides, preferably the bromides, e.g., dimethyl hexadecyl sulphonium bromide.

The selection of the monocation active treating agent is adapted to the original roughness or smoothness of the fiber, subject to the smoothness required for the treatment;

In general, those substances are preferred which do not discolor the fiber to any appreciable extent which anti-static effect if the chain These subsometimes happens in the case of pyridinium compounds. I

The concentration of the second bath may be roughly equal to that of the first bath, i.e., 0.5 to 2% by weight, calculated as dry matter. The treating temperature in the second bath may be room temperature or slightly higher.

Having described the present invention in its broader aspects a more detailed example of the procedure in accordance therewith is now given in order to assist in a better understanding of its various ramifications, it being understood that this is included herein for purpose of illustration rather than limitation. Percentages are by weight throughout the specification and claims unless otherwise specified.

Example A quantity of one hundred kilograms of polyamide fibers having an elementary titre of 1.4 denier and an average length of 38 mm., produced from polymerized epsilon caprolactam by melt spinning, was immersed during five minutes in an aqueous solution of polymethylacrylic acid of 1% by weight. The pH of the bath was maintained at 3.5 while the temperature was kept at 90 C. The bath ratio was 1 to 10. The treated fibers were then subjected to centrifuging until the fibers still contained about 20% moisture. Thereafter the centn'fuged material in still a moist condition was immersed for a period of five minutes in a solution of 1% by weight of the monomeric monocation active substance. The solution contained 95 parts by weight of lauryl trimethyl ammonium chloride and 5 parts by weight of an ethoxylated stearic acid amide converted into the quaternary ammonium compound by dimethyl sulphate. Subsequent to the second treating bath the fiber material was again subjected to centrifuging and thereafter dried at C. The resultant material was found to be quite smooth and very suitable for carding. The material was carded using a normal card clothing at the usual speed with only small quantities of fibers remaining in the card.

The aforementioned treating agents are to a certain degree firmly connected with the fiber so that they are not removed by a soap solution or by hot water. However, they might be removed by hot salt solutions, such as sodium chloride or sodium sulphate solutions of 1 to 5% or by dilute acids. After the treating agents have exercised the required influence, they may be removed from the fibers at a subsequent treatment stage.

Summarizing, the present invention is based upon a new process of treating synthetic fiber material and more particularly polyamides with a polymeric polyactive compound and then subsequently with a monomeric monoactive substance.

While the invention has been described in terms of preferred embodiments thereof, it is to be understood that considerable variations from the details disclosed herein might be made without departing from the true scope and spirit of the invention. Accordingly, the invention is to be limited only by the claims set forth hereinafter.

What is claimed is:

1. A process for the manufacture of polyamide fibers having an improved cardability comprising impregnating the polyamide fibers with an aqueous acidic solution of a water-soluble polyanion-active polyvinyl compound to effect a resultant anionic activity on said fibers, thereafter subjecting the impregnated wet polyamide fibers to the action of an alkyl trimethyl ammonium compound, and

'then drying the polyamide fibers.

References Cited in the file of this patent UNITED STATES PATENTS 2,343,095 Smith Feb. 29, 1944 2,381,020 Wilkes Aug. 7, 1945 2,468,086 Latham Apr. 26, 1949 2,741,568 Hayek Apr. 10, 1956 

1. A PROCESS FOR THE MANUFACTURE OF POLYAMIDE FIBERS HAVING AN IMPROVED CARDABILITY COMPRISING IMPREGNATING THE POLYAMIDE FIBERS WITH AN AQUEOUS ACIDIC SOLUTION OF A WATER-SOLUBLE POLYANION-ACTIVE POLYVINYL COMPOUND TO EFFECT A RESULTANT ANIONIC ACTIVITY ON SAID FIBERS, THEREAFTER SUBJECTING THE IMPREGNATED WET POLYAMIDE FIBERS TO THE ACTION OF AN ALKYL TRIMETHYL AMMONIUM COMPOUND, AND THEN DRYING THE POLYAMIDE FIBERS. 